This invention relates to radiant hydronic systems using metal plates that are heated or cooled by attached tubing that is fed hot or cold water for heating and/or cooling dwellings, offices, etc., the metal plates being held in the floor, walls or ceiling of a room as part of an assembly of modular panels into which the tubing is inserted so that the plates radiate heat to the room when the tubing is fed hot water, to heat the room; or absorbs heat from the room by radiation when the tubing is fed cold water, to cool the room; the tubing being secured in the panels in intimate thermal contact with the radiation plate and covered by a finished floor, wall or ceiling of the room.
In particular, a set of two or more of such modular panels are connected together by hinges so that the set is unfolded for installation by attachment to a floor, wall or ceiling followed by insertion of the tubing for heating and/or cooling.